Technical Field
The present invention relates to a method for producing a sulfide solid electrolyte.
Background Art
With the rapid spread of information-related devices and communication devices in recent years, great importance has been attached to the development of batteries that can be used as the power source of such devices. In the automobile industry, etc., high-output and high-capacity batteries for electric vehicles or hybrid vehicles are under development. Among various kinds of batteries under development, a lithium battery has attracted attention, from the viewpoint of its high energy density.
Currently, in a general lithium battery, a separator is used to separate a cathode and an anode from each other and is impregnated with an electrolyte that contains an organic solvent. Therefore, it is needed to increase the thickness of the separator. Accordingly, there is a problem that the separator accounts for a large proportion of the battery and results in low energy density. In the case of an all-solid-state lithium battery that uses a solid electrolyte layer in place of a liquid electrolyte, the thickness of the solid electrolyte layer that also serves as the separator can be decreased, so that the battery is excellent in terms of energy density. Also, a sulfide solid electrolyte is known as a solid electrolyte that is used in such a solid electrolyte layer.
Since the sulfide solid electrolyte has high lithium ion conductivity, it is useful for increasing battery output, and various studies have been made. For example, a production method is disclosed in Patent Document 1, in which a sulfide glass is obtained by non-crystallizing a raw material composition that contains at least Li2S, P2S5, LiI and LiBr, and the sulfide glass is heated at 195° C. or more, thereby obtaining a sulfide solid electrolyte material with high lithium ion conductivity.
Patent Document 1: Japanese Patent Application Laid-Open No. 2015-11898